AP Exam ReviewAP Exam ReviewCellsCells

Prokaryotic vs. Eukaryotic Prokaryotic vs. Eukaryotic CellsCells

ProkaryoteProkaryote ““before” “nucleus”before” “nucleus” BacteriaBacteria DNA is concentrated in nucleoid (non DNA is concentrated in nucleoid (non

membrane-bound)membrane-bound) No membrane bound organellesNo membrane bound organelles

EukaryoteEukaryote ““true” “nucleus”true” “nucleus” Protists, plants, fungi, animalsProtists, plants, fungi, animals Nucleus holds DNANucleus holds DNA Membrane bound organellesMembrane bound organelles

Cellular OrganellesCellular Organelles Nucleus:Nucleus:

““control center” of control center” of the cellthe cell

Surrounded by a Surrounded by a nuclear envelopenuclear envelope

DNADNA Nucleolus: site of Nucleolus: site of

ribosome synthesisribosome synthesis

Cellular OrganellesCellular Organelles

RibosomesRibosomes Site of protein assemblySite of protein assembly Free and bound ribosomesFree and bound ribosomes

Cellular OrganellesCellular Organelles Endoplasmic Reticulum:Endoplasmic Reticulum:

Made up of membranous tubules and Made up of membranous tubules and cisternae (sacs)cisternae (sacs)

Smooth ER: NO ribosomes attachedSmooth ER: NO ribosomes attached Synthesis of lipidsSynthesis of lipids Metabolism of carbsMetabolism of carbs Detoxification of drugs and other poisonsDetoxification of drugs and other poisons

Rough ER: ribosomes attachedRough ER: ribosomes attached Protein assemblyProtein assembly

Cellular OrganellesCellular Organelles Smooth and Rough Smooth and Rough

ERER

Cellular OrganellesCellular Organelles Golgi Apparatus:Golgi Apparatus:

Products of the Products of the Endoplasmic Endoplasmic Reticulum are Reticulum are modified and stored modified and stored herehere

Cellular OrganellesCellular Organelles Lysosomes:Lysosomes:

Used by cells to Used by cells to digest digest macromoleculesmacromolecules

Sac of Sac of hydrolytichydrolytic enzymesenzymes

Apoptosis: Apoptosis: Programmed cell Programmed cell

deathdeath

Cellular OrganellesCellular Organelles Vacuoles:Vacuoles:

Food vacuoles Food vacuoles (storage)(storage)

Contractile vacuoles Contractile vacuoles (pump extra water (pump extra water out of cells in out of cells in freshwater protists)freshwater protists)

Central vacuole Central vacuole (plant cells)(plant cells)

Stores organic Stores organic compounds, compounds, inorganic ions (K+, inorganic ions (K+, Cl-), and waterCl-), and water

Cellular OrganellesCellular Organelles Peroxisomes:Peroxisomes:

Contain enzymes that transfer hydrogen Contain enzymes that transfer hydrogen from various substances to oxygen, from various substances to oxygen, producing Hproducing H22OO22 as a byproduct as a byproduct

Various functions:Various functions: Break fatty acids down into smaller Break fatty acids down into smaller

molecules for cellular respirationmolecules for cellular respiration Detoxify alcohol in liverDetoxify alcohol in liver

Cellular OrganellesCellular Organelles MitochondriaMitochondria

Site of cellular Site of cellular respirationrespiration

““powerhouse of the powerhouse of the cell”cell”

More metabolic More metabolic activity = more activity = more mitochondriamitochondria

Cellular OrganellesCellular Organelles Mitochondrial Mitochondrial

Structure:Structure: Outer membraneOuter membrane Inner membrane:Inner membrane:

Cristae = large Cristae = large surface areasurface area

Intermembrane Intermembrane spacespace

Mitochondrial Mitochondrial matrixmatrix

Cellular OrganellesCellular Organelles Chloroplasts:Chloroplasts:

Found in plants and Found in plants and eukaryotic algaeeukaryotic algae

Site of Site of photosynthesisphotosynthesis

Contain the green Contain the green pigment chlorophyllpigment chlorophyll

Cellular OrganellesCellular Organelles Chloroplast Chloroplast

StructureStructure ThylakoidsThylakoids

Grana = stacks of Grana = stacks of thylakoidsthylakoids

StromaStroma Fluid outside the Fluid outside the

thylakoidsthylakoids

Cellular OrganellesCellular Organelles CytoskeletonCytoskeleton

Maintains shape of Maintains shape of cellcell

Responsible for Responsible for movement of cell movement of cell and movement of and movement of organelles within organelles within cellcell

Railroad ideaRailroad idea

Cellular OrganellesCellular Organelles Components of Cytoskeleton:Components of Cytoskeleton:

Microtubules – 25 nm diameterMicrotubules – 25 nm diameter Intermediate Filaments – 8 – 12 nm Intermediate Filaments – 8 – 12 nm

diameterdiameter Microfilaments – 7 nm diameterMicrofilaments – 7 nm diameter

Cellular OrganellesCellular Organelles MicrotubulesMicrotubules

Hollow tubesHollow tubes Made up of A- and B-tubulinMade up of A- and B-tubulin Responsible for:Responsible for:

Cell motility (cilia/flagella)Cell motility (cilia/flagella) Chromosome movements (mitosis)Chromosome movements (mitosis) Movement of organellesMovement of organelles Maintenance of cell shapeMaintenance of cell shape

Cellular OrganellesCellular Organelles Intermediate FilamentsIntermediate Filaments

Made up of fibrous proteinsMade up of fibrous proteins Made up of keratinMade up of keratin Responsible for:Responsible for:

Structural supportStructural support Maintenance of cell shapeMaintenance of cell shape

Cellular OrganellesCellular Organelles MicrofilamentsMicrofilaments

Made up of 2 intertwined strands of actinMade up of 2 intertwined strands of actin Responsible for:Responsible for:

Muscle contractionMuscle contraction Cytoplasmic streamingCytoplasmic streaming Cell motility (pseudopodia)Cell motility (pseudopodia) Cell division (cleavage furrow)Cell division (cleavage furrow) Maintenance of/changes in cell shapeMaintenance of/changes in cell shape

Cellular OrganellesCellular Organelles Cell WallCell Wall

Found only in plant Found only in plant cellscells

Protects the cell wallProtects the cell wall Maintains cell shapeMaintains cell shape Prevents excessive Prevents excessive

uptake of wateruptake of water Hold plant up against Hold plant up against

gravitygravity

Cellular OrganellesCellular Organelles Extracellular Matrix:Extracellular Matrix:

Found in animal cellsFound in animal cells Made up of Made up of

glycoproteins glycoproteins (collagen) & (collagen) & proteoglycansproteoglycans

Proteins + carbohydratesProteins + carbohydrates Provides support and Provides support and

anchorage for cellsanchorage for cells Differs from one cell Differs from one cell

type to anothertype to another

Intercellular JunctionsIntercellular Junctions Neighboring cells Neighboring cells

are connected to are connected to one anotherone another

Plant cells:Plant cells: Plasmodesmata:Plasmodesmata:

Channels in the cell Channels in the cell wall through which wall through which strands of cytoplasm strands of cytoplasm pass through and pass through and connect the living connect the living contents of adjacent contents of adjacent cellscells

Intercellular JunctionsIntercellular Junctions Animal Cells:Animal Cells:

Tight junctionsTight junctions DesmosomesDesmosomes Gap junctionsGap junctions

Intercellular JunctionsIntercellular Junctions Tight junctions:Tight junctions:

Membranes of Membranes of neighboring cells neighboring cells are fusedare fused

Form a continuous Form a continuous “belt” around a cell“belt” around a cell

Example: digestive Example: digestive tracttract

Intercellular JunctionsIntercellular Junctions DesmosomesDesmosomes

Anchoring junctionsAnchoring junctions Act as rivetsAct as rivets

Intercellular JunctionsIntercellular Junctions Gap junctionsGap junctions

Communicating Communicating junctionsjunctions

Cytoplasmic Cytoplasmic channels between channels between adjacent cellsadjacent cells

Salts, sugars, AAs, Salts, sugars, AAs, etc. can pass etc. can pass throughthrough

Diffusion vs. OsmosisDiffusion vs. OsmosisDiffusion:Movement of molecules from

high to low concentration until equilibrium is reached.

Passive Transport= no energy required

What substances may diffuse across membrane? Nonpolar (non-charged) molecules; small polar molecules

Osmosis:The passive transport of water across a selectively permeable membraneHyper-, hypo-, iso- tonic

RELATIVE TERMS!!Always referring to solute concentration

Water moves from areas of lower concentration of solutes (hypotonic) to areas of higher solute concentration (hypertonic)

MitosisMitosis